- Bird-users - Mailing Lists

2 bugs 1 network
by alpha_one_x86 09 Apr '22

09 Apr '22

Hi, I have very buggy network with bird and OSPF, I try not restart bird daemon to catch the bugs: 1) on some router, birdc show ospf topology all change constantly See attached file 2) Route A (emit route to X.X.X.X) <-> Router B <-> Router C (Bug received route to X.X.X.X via B) on router B I put export filter protocol ospf main { import all; export filter { #STARTEXPORTFILTER if net = X.X.X.X/32 then reject; #STOPEXPORTFILTER accept; }; It's complex network with multiple router, and edge router have BGP. Cheers, -- alpha_one_x86/BRULE Herman<alpha_one_x86(a)first-world.info> Main developer of Supercopier/Ultracopier/CatchChallenger, Esourcing and server management IT, OS, technologies, research & development, security and business department

1 0

OSPFv2 Unnumbered -- Am I doing it right?
by Bernd Naumann 01 Apr '22

01 Apr '22

Hi Users of BIRD! I have only heard about "OSPF Unnumbered" a couple of times, and never have seen any clear explanation or specific details. And based on that, I had the false assumption that "unnumbered" would imply "having no address on the interfaces"; maybe only an IPv4 address used as a router-id as an `/32' assignment on loopback. But without an address on an interface I have not seen any packets sent to 224.0.0.5. So I just gave it a try and added the `/32` from loopback on each interface, too, and from the BIRD documentation I concluded I must set `type ptp;` in the ospf area interface stanza... and.... Bingo. It just works. Later I discovered, that's the way how Cumulus recommends it with FRR. [1] But couldn't have anyone told me this earlier? Next time maybe :) So basically my question is: Is this the correct way as it is intended? Is OSPFv2 unnumbered --how ever-- properly specified, or just a clever way, which just happens to work? And: Is this compatible with NOS from various vendors? (As IPv6 offers link-local addresses, there is no need for OSPFv3 unnumbered, right?) Are there any issues with that approach I'm unaware of? Thanks for your time, and have a nice Friday evening and weekend. Bernd PS: I tried this on Debian 11 with kernel 5.10 and bird 2.0.9 [1] https://docs.nvidia.com/networking-ethernet-software/cumulus-linux-50/Layer…

1 0

BFD: Socket Error Operation not permitted on bird 2.0.8
by Irene Lalioti 01 Apr '22

01 Apr '22

Hello dear community, I would like to pose a question regarding the error I receive concerning BFD : socket operation not permitted. The bfd is configured with multiplier 3; interval 300ms; idle tx interval 1 sec; Thanks a lot for your feedback in advance! Irena -- Irene Lalioti Network Engineer Fondation RESTENA 2, avenue de l'Université L-4365 Esch/Alzette Tel: +352 424409 1 Fax: +352 422473 This email may contain information for limited distribution only, please treat accordingly.

2 2

Bird setting TTL to 1 at the end of a passive BGP session opening
by Rumen Telbizov 01 Apr '22

01 Apr '22

Hello Bird users, First time poster and new subscriber. I noticed something strange and wanted to report it here in case this is in fact a bug that deserves attention. I run bird 2.0.7-4.1 on Debian 11. I have a BGP section configured as passive that acts as a TCP health-check endpoint. It is as follows: *--- cut --* protocol bgp HEALTHCHECKv4 { hold time 6; startup hold time 20; connect delay time 3; connect retry time 6; error wait time 3, 12; passive on; local 100.64.0.5 as 65000; neighbor 100.64.0.4 as 65535; } *--- cut --* What ends up happening on the wire is this: *--- cut --* 23:15:09.443792 IP (tos 0x0, ttl 254, id 4040, offset 0, flags [DF], proto TCP (6), length 60) 100.64.0.4.16141 > 100.64.0.5.179: Flags [S], cksum 0xa78f (correct), seq 723435095, win 8961, options [mss 8621,sackOK,TS val 3290475421 ecr 0,nop,wscale 0], length 0 23:15:09.443823 IP (tos 0xc0, ttl 255, id 0, offset 0, flags [DF], proto TCP (6), length 60) 100.64.0.5.179 > 100.64.0.4.16141: Flags [S.], cksum 0xc8b7 (incorrect -> 0x0785), seq 124371865, ack 723435096, win 62643, options [mss 8961,sackOK,TS val 2210037294 ecr 3290475421,nop,wscale 7], length 0 23:15:09.444437 IP (tos 0x0, ttl 254, id 4041, offset 0, flags [DF], proto TCP (6), length 52) 100.64.0.4.16141 > 100.64.0.5.179: Flags [.], cksum 0x2550 (correct), seq 1, ack 1, win 8961, options [nop,nop,TS val 3290475422 ecr 2210037294], length 0 23:15:09.444471 IP (tos 0x0, ttl 254, id 4042, offset 0, flags [DF], proto TCP (6), length 52) 100.64.0.4.16141 > 100.64.0.5.179: Flags [F.], cksum 0x254e (correct), seq 1, ack 1, win 8961, options [nop,nop,TS val 3290475423 ecr 2210037294], length 0 23:15:09.444576 IP (tos 0xc0, *ttl 1*, id 55411, offset 0, flags [DF], proto TCP (6), length 99) 100.64.0.5.179 > 100.64.0.4.16141: Flags [P.], cksum 0xc8de (incorrect -> 0x58b6), seq 1:48, ack 2, win 490, options [nop,nop,TS val 2210037294 ecr 3290475423], length 47: BGP Open Message (1), length: 47 Version 4, my AS 65000, Holdtime 6s, ID 100.64.0.5 Optional parameters, length: 18 Option Capabilities Advertisement (2), length: 16 Route Refresh (2), length: 0 Graceful Restart (64), length: 2 Restart Flags: [none], Restart Time 120s 0x0000: 0078 32-Bit AS Number (65), length: 4 4 Byte AS 65000 0x0000: 0000 fde8 Enhanced Route Refresh (70), length: 0 no decoder for Capability 70 Long-lived Graceful Restart (71), length: 0 23:15:09.444602 IP (tos 0xc0, *ttl 1*, id 55412, offset 0, flags [DF], proto TCP (6), length 52) 100.64.0.5.179 > 100.64.0.4.16141: Flags [F.], cksum 0xc8af (incorrect -> 0x4635), seq 48, ack 2, win 490, options [nop,nop,TS val 2210037294 ecr 3290475423], length 0 23:15:09.444670 IP (tos 0x0, ttl 64, id 1, offset 0, flags [none], proto ICMP (1), length 56) 100.64.0.4 > 100.64.0.5: ICMP time exceeded in-transit, length 36 IP (tos 0xc0, ttl 1, id 55411, offset 0, flags [DF], proto TCP (6), length 99) 100.64.0.5.179 > 100.64.0.4.16141: [|tcp] *--- cut --* As you can see the TTL on our packets is initially set to 255. At the end of the connection during the last PUSH and FIN packets all of a sudden bird sets the TTL to 1. I have no ttl security enabled and even if I explicitly disable it the problem persists. A workaround that I found to work is to pass multihop 20 directive which then changes the ttl 1 above to ttl 20 which alleviates the problem. Let me know if you need any additional information. Regards, -- Rumen Telbizov Site Reliability Engineer <http://telbizov.com/>

4 3

[RFCv2] Babel: add v4viav6 support
by Andreas Rammhold 01 Apr '22

01 Apr '22

This implements [draft-ietf-babel-v4viav6] an IPv4 via IPv6 extension to the Babel routing protocol that allows annoncing routes to an IPv4 prefix with an IPv6 next-hop, which makes it possible for IPv4 traffic to flow through interfaces that have not been assigned an IPv4 address. The implementation is compatible with the current Babeld version (the relevant changes can be seen in the [babeld PR]). I've verified this with a few VMs in the following setup: Bird <- v4 only -> Bird <- v6 only -> Babeld <- v4 only -> Babeld Each routing daemon was running on their own VM and had L2 connectivity to only its direct neighbors. At the nodes at the edges v4 networks have been announced and full end-to-end communication was possible over the mixed AF network. The v6 only link between Babel and Bird (at the "center" of the above setup) did transport the v4 packets via the v6 link-local next hop addresses just as expected. Thanks to Toke Høiland-Jørgensen for early review on this work. [draft-ietf-babel-v4viav6]: https://datatracker.ietf.org/doc/draft-ietf-babel-v4viav6/ [babeld PR]: https://github.com/jech/babeld/pull/56 --- The draft has reached the "Proposed Standard" stage: https://mailarchive.ietf.org/arch/msg/ietf-announce/oybMxQbud2RvpyBBn8hkMTK… The mentioned babeld PR has been merged and a new babel release has been cut a few hours ago. I've addressed the feedback gathered in 2020 when I posted this for the first time. On the topic of "feature detection" I didn't invest any more time. It seems like the conclusion was that the adminitrator has to ensure that the host system provides the required capabilities. If it doesn't then we don't try to disable features. I've rebased this onto Bird 2.0.9 and rerun my test suite. Everything looks fine. doc/bird.sgml | 6 +++ proto/babel/babel.c | 26 ++++++++-- proto/babel/babel.h | 3 ++ proto/babel/config.Y | 5 +- proto/babel/packets.c | 114 ++++++++++++++++++++++++++++++------------ 5 files changed, 116 insertions(+), 38 deletions(-) diff --git a/doc/bird.sgml b/doc/bird.sgml index 1d5ae056..14758627 100644 --- a/doc/bird.sgml +++ b/doc/bird.sgml @@ -1892,6 +1892,7 @@ protocol babel [<name>] { algorithm ( hmac sha1 | hmac sha256 | hmac sha384 | hmac sha512 | blake2s128 | blake2s256 | blake2b256 | blake2b512 ); }; + ipv4 via ipv6 <switch>; }; } </code> @@ -2000,6 +2001,11 @@ protocol babel [<name>] { protocol will only accept HMAC-based algorithms or one of the Blake algorithms, and the length of the supplied password string must match the key size used by the selected algorithm. + + <tag><label id="babel-ipv4-via-ipv6">ipv4 via ipv6 <m/switch/</tag> + If enabled, Bird will accept and emit IPv4-via-IPv6 routes when IPv4 + addresses are absent from the interface as described in draft-ietf-babel-v4viav6. + Default: yes. </descrip> <sect1>Attributes diff --git a/proto/babel/babel.c b/proto/babel/babel.c index 174fc9e2..cba407e3 100644 --- a/proto/babel/babel.c +++ b/proto/babel/babel.c @@ -965,8 +965,17 @@ babel_send_update_(struct babel_iface *ifa, btime changed, struct fib *rtable) msg.update.router_id = e->router_id; net_copy(&msg.update.net, e->n.addr); - msg.update.next_hop = ((e->n.addr->type == NET_IP4) ? - ifa->next_hop_ip4 : ifa->next_hop_ip6); + if (e->n.addr->type == NET_IP4) { + /* Always prefer v4 nexthop if set */ + if(!ipa_zero(ifa->next_hop_ip4)) + msg.update.next_hop = ifa->next_hop_ip4; + + /* Only send v4-via-v6 if enabled */ + else if (ifa->cf->ip4_via_ip6) + msg.update.next_hop = ifa->next_hop_ip6; + } else { + msg.update.next_hop = ifa->next_hop_ip6; + } /* Do not send route if next hop is unknown, e.g. no configured IPv4 address */ if (ipa_zero(msg.update.next_hop)) @@ -1261,6 +1270,12 @@ babel_handle_update(union babel_msg *m, struct babel_iface *ifa) return; } + /* Reject IPv4 via IPv6 routes if disabled */ + if (!ifa->cf->ip4_via_ip6 && msg->net.type == NET_IP4 && ipa_is_ip6(msg->next_hop)) { + DBG("Babel: Ignoring disabled IPv4 via IPv6 route.\n"); + return; + } + /* Regular update */ e = babel_get_entry(p, &msg->net); r = babel_get_route(p, e, nbr); /* the route entry indexed by neighbour */ @@ -1666,7 +1681,7 @@ babel_iface_update_addr4(struct babel_iface *ifa) ip_addr addr4 = ifa->iface->addr4 ? ifa->iface->addr4->ip : IPA_NONE; ifa->next_hop_ip4 = ipa_nonzero(ifa->cf->next_hop_ip4) ? ifa->cf->next_hop_ip4 : addr4; - if (ipa_zero(ifa->next_hop_ip4) && p->ip4_channel) + if (ipa_zero(ifa->next_hop_ip4) && p->ip4_channel && !ifa->cf->ip4_via_ip6) log(L_WARN "%s: Missing IPv4 next hop address for %s", p->p.name, ifa->ifname); if (ifa->up) @@ -2049,8 +2064,8 @@ babel_show_interfaces(struct proto *P, const char *iff) } cli_msg(-1023, "%s:", p->p.name); - cli_msg(-1023, "%-10s %-6s %-5s %7s %6s %7s %-15s %s", - "Interface", "State", "Auth", "RX cost", "Nbrs", "Timer", + cli_msg(-1023, "%-10s %-6s %-5s %-12s %7s %6s %7s %-15s %s", + "Interface", "State", "Auth", "IPv4 via Ip6", "RX cost", "Nbrs", "Timer", "Next hop (v4)", "Next hop (v6)"); WALK_LIST(ifa, p->interfaces) @@ -2067,6 +2082,7 @@ babel_show_interfaces(struct proto *P, const char *iff) ifa->iface->name, (ifa->up ? "Up" : "Down"), (ifa->cf->auth_type == BABEL_AUTH_MAC ? (ifa->cf->auth_permissive ? "Perm" : "Yes") : "No"), + (ifa->cf->ip4_via_ip6 ? "Yes" : "No"), ifa->cf->rxcost, nbrs, MAX(timer, 0), ifa->next_hop_ip4, ifa->next_hop_ip6); } diff --git a/proto/babel/babel.h b/proto/babel/babel.h index 84feb085..191f734e 100644 --- a/proto/babel/babel.h +++ b/proto/babel/babel.h @@ -111,6 +111,7 @@ enum babel_ae_type { BABEL_AE_IP4 = 1, BABEL_AE_IP6 = 2, BABEL_AE_IP6_LL = 3, + BABEL_AE_IPV4_VIA_IPV6 = 4, BABEL_AE_MAX }; @@ -150,6 +151,8 @@ struct babel_iface_config { uint mac_num_keys; /* Number of configured HMAC keys */ uint mac_total_len; /* Total digest length for all configured keys */ list *passwords; /* Passwords for authentication */ + + u8 ip4_via_ip6; /* Enable IPv4 via IPv6 */ }; struct babel_proto { diff --git a/proto/babel/config.Y b/proto/babel/config.Y index 05210fa4..7190f099 100644 --- a/proto/babel/config.Y +++ b/proto/babel/config.Y @@ -25,7 +25,8 @@ CF_DECLS CF_KEYWORDS(BABEL, INTERFACE, METRIC, RXCOST, HELLO, UPDATE, INTERVAL, PORT, TYPE, WIRED, WIRELESS, RX, TX, BUFFER, PRIORITY, LENGTH, CHECK, LINK, NEXT, HOP, IPV4, IPV6, BABEL_METRIC, SHOW, INTERFACES, NEIGHBORS, - ENTRIES, RANDOMIZE, ROUTER, ID, AUTHENTICATION, NONE, MAC, PERMISSIVE) + ENTRIES, RANDOMIZE, ROUTER, ID, AUTHENTICATION, NONE, MAC, PERMISSIVE, + VIA) CF_GRAMMAR @@ -67,6 +68,7 @@ babel_iface_start: BABEL_IFACE->tx_tos = IP_PREC_INTERNET_CONTROL; BABEL_IFACE->tx_priority = sk_priority_control; BABEL_IFACE->check_link = 1; + BABEL_IFACE->ip4_via_ip6 = 1; }; @@ -143,6 +145,7 @@ babel_iface_item: | CHECK LINK bool { BABEL_IFACE->check_link = $3; } | NEXT HOP IPV4 ipa { BABEL_IFACE->next_hop_ip4 = $4; if (!ipa_is_ip4($4)) cf_error("Must be an IPv4 address"); } | NEXT HOP IPV6 ipa { BABEL_IFACE->next_hop_ip6 = $4; if (!ipa_is_ip6($4)) cf_error("Must be an IPv6 address"); } + | IPV4 VIA IPV6 bool { BABEL_IFACE->ip4_via_ip6 = $4; } | AUTHENTICATION NONE { BABEL_IFACE->auth_type = BABEL_AUTH_NONE; } | AUTHENTICATION MAC { BABEL_IFACE->auth_type = BABEL_AUTH_MAC; BABEL_IFACE->auth_permissive = 0; } | AUTHENTICATION MAC PERMISSIVE { BABEL_IFACE->auth_type = BABEL_AUTH_MAC; BABEL_IFACE->auth_permissive = 1; } diff --git a/proto/babel/packets.c b/proto/babel/packets.c index f13410e2..4b2acc64 100644 --- a/proto/babel/packets.c +++ b/proto/babel/packets.c @@ -167,9 +167,11 @@ struct babel_parse_state { u64 router_id; /* Router ID used in subsequent updates */ u8 def_ip6_prefix[16]; /* Implicit IPv6 prefix in network order */ u8 def_ip4_prefix[4]; /* Implicit IPv4 prefix in network order */ + u8 def_ip4viaip6_prefix[4]; /* Implicit IPv4 prefix in network order */ u8 router_id_seen; /* router_id field is valid */ u8 def_ip6_prefix_seen; /* def_ip6_prefix is valid */ u8 def_ip4_prefix_seen; /* def_ip4_prefix is valid */ + u8 def_ip4viaip6_prefix_seen; /* def_ip4viaip6_prefix is valid*/ u8 current_tlv_endpos; /* End of self-terminating TLVs (offset from start) */ u8 sadr_enabled; u8 is_unicast; @@ -515,9 +517,6 @@ babel_read_ihu(struct babel_tlv *hdr, union babel_msg *m, msg->addr = IPA_NONE; msg->sender = state->saddr; - if (msg->ae >= BABEL_AE_MAX) - return PARSE_IGNORE; - /* * We only actually read link-local IPs. In every other case, the addr field * will be 0 but validation will succeed. The handler takes care of these @@ -530,13 +529,13 @@ babel_read_ihu(struct babel_tlv *hdr, union babel_msg *m, if (TLV_OPT_LENGTH(tlv) < 4) return PARSE_ERROR; state->current_tlv_endpos += 4; - break; + return PARSE_SUCCESS; case BABEL_AE_IP6: if (TLV_OPT_LENGTH(tlv) < 16) return PARSE_ERROR; state->current_tlv_endpos += 16; - break; + return PARSE_SUCCESS; case BABEL_AE_IP6_LL: if (TLV_OPT_LENGTH(tlv) < 8) @@ -544,10 +543,10 @@ babel_read_ihu(struct babel_tlv *hdr, union babel_msg *m, msg->addr = ipa_from_ip6(get_ip6_ll(&tlv->addr)); state->current_tlv_endpos += 8; - break; + return PARSE_SUCCESS; } - return PARSE_SUCCESS; + return PARSE_IGNORE; } static uint @@ -647,6 +646,47 @@ babel_read_next_hop(struct babel_tlv *hdr, union babel_msg *m UNUSED, return PARSE_IGNORE; } + +/* This is called directly from babel_read_next_hop to handle the ip4 address + compression state */ +static int +babel_get_ip4_prefix(struct babel_tlv_update *tlv, + struct babel_msg_update *msg, + u8 *def_prefix_seen, + u8 (*def_prefix)[], + ip_addr next_hop, + int len) +{ + if (tlv->plen > IP4_MAX_PREFIX_LENGTH) + return PARSE_ERROR; + + /* Cannot omit data if there is no saved prefix */ + if (tlv->omitted && !*def_prefix_seen) + return PARSE_ERROR; + + /* Update must have next hop, unless it is retraction */ + if (ipa_zero(next_hop) && msg->metric != BABEL_INFINITY) + return PARSE_IGNORE; + + /* Merge saved prefix and received prefix parts */ + u8 buf[4] = {}; + memcpy(buf, *def_prefix, tlv->omitted); + memcpy(buf + tlv->omitted, tlv->addr, len); + + ip4_addr prefix4 = get_ip4(buf); + net_fill_ip4(&msg->net, prefix4, tlv->plen); + + if (tlv->flags & BABEL_UF_DEF_PREFIX) + { + put_ip4(*def_prefix, prefix4); + *def_prefix_seen = 1; + } + + msg->next_hop = next_hop; + + return PARSE_SUCCESS; +} + /* This is called directly from babel_write_update() and returns -1 if a next hop should be written but there is not enough space. */ static int @@ -696,6 +736,7 @@ static int babel_read_update(struct babel_tlv *hdr, union babel_msg *m, struct babel_parse_state *state) { + int rc; struct babel_tlv_update *tlv = (void *) hdr; struct babel_msg_update *msg = &m->update; @@ -706,7 +747,6 @@ babel_read_update(struct babel_tlv *hdr, union babel_msg *m, /* Length of received prefix data without omitted part */ int len = BYTES(tlv->plen) - (int) tlv->omitted; - u8 buf[16] = {}; if ((len < 0) || ((uint) len > TLV_OPT_LENGTH(tlv))) return PARSE_ERROR; @@ -724,31 +764,20 @@ babel_read_update(struct babel_tlv *hdr, union babel_msg *m, break; case BABEL_AE_IP4: - if (tlv->plen > IP4_MAX_PREFIX_LENGTH) - return PARSE_ERROR; - - /* Cannot omit data if there is no saved prefix */ - if (tlv->omitted && !state->def_ip4_prefix_seen) - return PARSE_ERROR; - - /* Update must have next hop, unless it is retraction */ - if (ipa_zero(state->next_hop_ip4) && (msg->metric != BABEL_INFINITY)) - return PARSE_IGNORE; - - /* Merge saved prefix and received prefix parts */ - memcpy(buf, state->def_ip4_prefix, tlv->omitted); - memcpy(buf + tlv->omitted, tlv->addr, len); - - ip4_addr prefix4 = get_ip4(buf); - net_fill_ip4(&msg->net, prefix4, tlv->plen); + rc = babel_get_ip4_prefix(tlv, msg, &state->def_ip4_prefix_seen, + &state->def_ip4_prefix, state->next_hop_ip4, + len); + if (rc != PARSE_SUCCESS) + return rc; - if (tlv->flags & BABEL_UF_DEF_PREFIX) - { - put_ip4(state->def_ip4_prefix, prefix4); - state->def_ip4_prefix_seen = 1; - } + break; - msg->next_hop = state->next_hop_ip4; + case BABEL_AE_IPV4_VIA_IPV6: + rc = babel_get_ip4_prefix(tlv, msg, &state->def_ip4viaip6_prefix_seen, + &state->def_ip4viaip6_prefix, state->next_hop_ip6, + len); + if (rc != PARSE_SUCCESS) + return rc; break; @@ -761,6 +790,7 @@ babel_read_update(struct babel_tlv *hdr, union babel_msg *m, return PARSE_ERROR; /* Merge saved prefix and received prefix parts */ + u8 buf[16] = {}; memcpy(buf, state->def_ip6_prefix, tlv->omitted); memcpy(buf + tlv->omitted, tlv->addr, len); @@ -863,7 +893,11 @@ babel_write_update(struct babel_tlv *hdr, union babel_msg *m, } else if (msg->net.type == NET_IP4) { - tlv->ae = BABEL_AE_IP4; + if (!ipa_zero(msg->next_hop) && ipa_is_ip6(msg->next_hop)) + tlv->ae = BABEL_AE_IPV4_VIA_IPV6; + else + tlv->ae = BABEL_AE_IP4; + tlv->plen = net4_pxlen(&msg->net); put_ip4_px(tlv->addr, &msg->net); } @@ -931,7 +965,15 @@ babel_read_route_request(struct babel_tlv *hdr, union babel_msg *m, msg->full = 1; return PARSE_SUCCESS; + /* + * When receiving requests, AEs 1 (IPv4) and 4 (v4-via-v6) MUST be + * treated in the same manner: the receiver processes the request as + * described in Section 3.8 of [RFC6126bis]. If an Update is sent, then + * it MAY be sent with AE 1 or 4, as described in Section 2.1 above, + * irrespective of which AE was used in the request. + */ case BABEL_AE_IP4: + case BABEL_AE_IPV4_VIA_IPV6: if (tlv->plen > IP4_MAX_PREFIX_LENGTH) return PARSE_ERROR; @@ -1032,7 +1074,15 @@ babel_read_seqno_request(struct babel_tlv *hdr, union babel_msg *m, case BABEL_AE_WILDCARD: return PARSE_ERROR; + /* + * When receiving requests, AEs 1 (IPv4) and 4 (v4-via-v6) MUST be + * treated in the same manner: the receiver processes the request as + * described in Section 3.8 of [RFC6126bis]. If an Update is sent, then + * it MAY be sent with AE 1 or 4, as described in Section 2.1 above, + * irrespective of which AE was used in the request. + */ case BABEL_AE_IP4: + case BABEL_AE_IPV4_VIA_IPV6: if (tlv->plen > IP4_MAX_PREFIX_LENGTH) return PARSE_ERROR; -- 2.35.1

2 2

Route export problem with FreeBSD 13.0
by Luiz Amaral 31 Mar '22

31 Mar '22

Hello guys, After upgrading one of my hosts from FreeBSD 12.2 to FreeBSD 13.0, I started noticing a problem when exporting routes to the KRT. My logs were getting flooded with "kernel: gw sdl_len too small". This message comes from cleanup_xaddrs_gateway() in sys/net/rtsock.c of releng/13.0, so I checked with "route monitor" and noticed that the blackhole routes and one interface route were the ones causing the message. got message of size 192 on Sat Aug 28 15:57:32 2021 RTM_ADD: Add Route: len 192, pid: 2293, seq 3, errno 22, flags:<UP,BLACKHOLE,PROTO1> locks: inits: sockaddrs: <DST,GATEWAY,NETMASK> 10.0.0.0 link#4 255.0.0.0 got message of size 192 on Sat Aug 28 15:57:32 2021 RTM_ADD: Add Route: len 192, pid: 2293, seq 4, errno 22, flags:<UP,PROTO1> locks: inits: sockaddrs: <DST,GATEWAY,NETMASK> 10.42.10.0 link#5 255.255.255.0 In BIRD they look the same as before the upgrade: bird> show route all 10.0.0.0/8 Table master4: 10.0.0.0/8 blackhole [s_null_4 2021-08-28 15:57:32] ! (200) Type: static univ bird> show route all 10.42.10.0/24 Table master4: 10.42.10.0/24 unicast [direct1 2021-08-28 16:07:59] ! (240) dev vlan10 Type: device univ I then decided to try manually adding a blackhole route using "route add -net 10.0.0.0/8 -blackhole -proto1 -nostatic", to get as close to what BIRD was trying to add and noticed that BIRD had a gateway, but "route add" didn't have one. got message of size 184 on Sat Aug 28 16:05:43 2021 RTM_ADD: Add Route: len 184, pid: 2766, seq 1, errno 0, flags:<UP,GATEWAY,DONE,BLACKHOLE,PROTO1> locks: inits: sockaddrs: <DST,NETMASK> 10.0.0.0 255.0.0.0 I tried commenting out line 324 in sysdep/bsd/krt-sock.c of v2.0.8 to see if that could fix it and bird was able to insert the blackhole route (can be seen below), but then bird started dying a couple seconds after starting up, with no error showing up on the logs. got message of size 184 on Sat Aug 28 15:27:33 2021 RTM_ADD: Add Route: len 184, pid: 46425, seq 2, errno 22, flags:<UP,PROTO1> locks: inits: sockaddrs: <DST,NETMASK> 10.42.10.0 255.255.255.0 got message of size 184 on Sat Aug 28 15:27:33 2021 RTM_ADD: Add Route: len 184, pid: 46425, seq 3, errno 0, flags:<UP,GATEWAY,DONE,BLACKHOLE,PROTO1> locks: inits: sockaddrs: <DST,NETMASK> 10.0.0.0 255.0.0.0 At this point, I ran out of ideas on what else to try. This is in a testing environment, so I can easily try things out or provide extra information. Thank you, Luiz

3 2

birdc show route output question
by Adam Thompson 30 Mar '22

30 Mar '22

Hi, I’m successfully using BIRD with the Go Looking Glass from https://github.com/xddxdd/bird-lg-go. I haven’t needed to use the birdc CLI until now, and I’m a bit confused by it in ways the docs don’t appear to address. (I’m running default distro pkgs on Alma Linux 8.5, one of the post-CentOS RHEL rebuilds.) The output I get looks like: [root@lg2 ~]# birdc show route | head BIRD 2.0.9 ready. Table master4: 223.94.242.0/23 unreachable [uwpg_rtr1_v4 2022-03-26 from 216.73.71.131] * (100) [AS56041?] unreachable [umrtr2_v4 2022-03-26 from 206.211.216.52] (100) [AS56041?] unreachable [umrtr1_v4 2022-03-26 from 206.211.216.51] (100) [AS56041?] 181.123.200.0/22 unreachable [umrtr1_v4 2022-03-26 from 206.211.216.51] * (100) [AS23201i] unreachable [umrtr2_v4 2022-03-26 from 206.211.216.52] (100) [AS23201i] unreachable [uwpg_rtr1_v4 2022-03-26 from 216.73.71.131] (100) [AS23201i] 88.218.186.0/24 unreachable [umrtr1_v4 2022-03-26 from 206.211.216.51] * (100) [AS62240i] unreachable [umrtr2_v4 2022-03-26 from 206.211.216.52] (100) [AS62240i] 1. Is the “unreachable” bit normal on a looking glass / route collector? 2. What’s with the “?” at the end of some ASes? 3. Where’s the AS paths? All I seem to get is the terminal AS. I’m not sure if I’m not using the tool correctly, or if I’m even using the right tool in the first place. Pointers / clues appreciated? Thanks, -Adam Adam Thompson Consultant, Infrastructure Services [MERLIN] 100 - 135 Innovation Drive Winnipeg, MB, R3T 6A8 (204) 977-6824 or 1-800-430-6404 (MB only) athompson(a)merlin.mb.ca<mailto:athompson@merlin.mb.ca> www.merlin.mb.ca<http://www.merlin.mb.ca/>

2 1

RFC: Upgrade filter integer size to 64-bit
by Maria Matejka 28 Mar '22

28 Mar '22

Dear fellow users of BIRD, I'd like to do a quick survey. BIRD now uses a 32-bit unsigned integer inside filters. OTOH, most of the integer route attributes are stored as uintptr_t, which is 32-bit or 64-bit depending on architecture. There are three basic options for further development: 1. Keep it as it is (32-bit filter integer, arch-dependent attribute integer). Pros: * Lesser memory footprint of route attributes on 32-bit archs Cons: * 8-byte attributes (currently only Babel RouterID) stored indirectly at least on 32-bit archs * Explicit checks and transformations between filters and attributes 2. Update both to 64 bits. Pros: * Much more convenient development Cons: * More memory eaten on 32-bit archs (actual ratio depends on how many route attributes you need to store) * Slower computation of arithmetics in filters on 32-bit archs 3. Make it completely arch-dependent, either both 64-bit or both 32-bit. Pros: * Uses both 32-bit and 64-bit archs in their intended way Cons: * Different behavior of filters on different archs * Possibly hard-to-discover architecture-dependent bugs If it was on me, I'd choose to update everything to 64 bits and just hope that the 32-bit use cases aren't affected too much. I suppose that nobody is running BIRD at a low memory 32-bit box having lots of routes in kernel with Linux kernel route metrics set, which is the worst case scenario I can think about. Is there anybody who would try to convince me that I shouldn't make filter integers and route attribute integers both 64 bits wide? Thank you all for your answers. Maria

7 7

[PATCH] Filter: Add support for setting TCP congestion control algorithm
by Trisha Biswas 25 Mar '22

25 Mar '22

Add support for setting the TCP congestion control algorithm per destination by modifying route attributes in BIRD. Previously supported kernel route attributes in BIRD were all integer values. Subsequently, this also adds string handling of kernel metrics. Usage: set krt_cc_algo in the BIRD filter configs. Allowed values can be found with net.ipv4.tcp_allowed_congestion_control. --- diff --git a/doc/bird.sgml b/doc/bird.sgml index 1d5ae056..310aef37 100644 --- a/doc/bird.sgml +++ b/doc/bird.sgml @@ -3377,7 +3377,7 @@ Supported attributes are: <cf/krt_sstresh/, <cf/krt_lock_sstresh/, <cf/krt_cwnd/, <cf/krt_lock_cwnd/, <cf/krt_advmss/, <cf/krt_lock_advmss/, <cf/krt_reordering/, <cf/krt_lock_reordering/, <cf/krt_hoplimit/, <cf/krt_lock_hoplimit/, <cf/krt_rto_min/, <cf/krt_lock_rto_min/, -<cf/krt_initcwnd/, <cf/krt_initrwnd/, <cf/krt_quickack/, +<cf/krt_initcwnd/, <cf/krt_initrwnd/, <cf/krt_quickack/, <cf/krt_cc_algo/, <cf/krt_feature_ecn/, <cf/krt_feature_allfrag/ <sect1>Example diff --git a/filter/config.Y b/filter/config.Y index 8916ea97..8916d08d 100644 --- a/filter/config.Y +++ b/filter/config.Y @@ -178,6 +178,9 @@ f_generate_empty(struct f_dynamic_attr dyn) case EAF_TYPE_LC_SET: empty = f_const_empty_lclist; break; + case EAF_TYPE_CC_ALGO: + empty = f_const_empty_cc_algo; + break; default: cf_error("Can't empty that attribute"); } @@ -816,6 +819,7 @@ term: | '-' EMPTY '-' { $$ = f_new_inst(FI_CONSTANT, f_const_empty_clist); } | '-' '-' EMPTY '-' '-' { $$ = f_new_inst(FI_CONSTANT, f_const_empty_eclist); } | '-' '-' '-' EMPTY '-' '-' '-' { $$ = f_new_inst(FI_CONSTANT, f_const_empty_lclist); } + | '-' '-' '-' '-' EMPTY '-' '-' '-' '-' { $$ = f_new_inst(FI_CONSTANT, f_const_empty_cc_algo); } | PREPEND '(' term ',' term ')' { $$ = f_new_inst(FI_PATH_PREPEND, $3, $5); } | ADD '(' term ',' term ')' { $$ = f_new_inst(FI_CLIST_ADD, $3, $5); } | DELETE '(' term ',' term ')' { $$ = f_new_inst(FI_CLIST_DEL, $3, $5); } diff --git a/filter/data.c b/filter/data.c index 56c1fb17..84e91d59 100644 --- a/filter/data.c +++ b/filter/data.c @@ -91,6 +91,9 @@ const struct f_val f_const_empty_path = { }, f_const_empty_lclist = { .type = T_LCLIST, .val.ad = &null_adata, +}, f_const_empty_cc_algo = { + .type = T_STRING, + .val.ad = &null_adata, }; static struct adata * diff --git a/filter/data.h b/filter/data.h index 4cb6b7a8..46216e92 100644 --- a/filter/data.h +++ b/filter/data.h @@ -262,6 +262,7 @@ trie_match_next_longest_ip6(net_addr_ip6 *n, ip6_addr *found) #define F_CMP_ERROR 999 +#define TCP_CA_NAME_MAX 16 const char *f_type_name(enum f_type t); @@ -297,7 +298,7 @@ undef_value(struct f_val v) (v.val.ad == &null_adata); } -extern const struct f_val f_const_empty_path, f_const_empty_clist, f_const_empty_eclist, f_const_empty_lclist; +extern const struct f_val f_const_empty_path, f_const_empty_clist, f_const_empty_eclist, f_const_empty_lclist, f_const_empty_cc_algo; enum filter_return f_eval(const struct f_line *expr, struct linpool *tmp_pool, struct f_val *pres); diff --git a/filter/f-inst.c b/filter/f-inst.c index 901d2939..735c643a 100644 --- a/filter/f-inst.c +++ b/filter/f-inst.c @@ -709,6 +709,9 @@ case EAF_TYPE_LC_SET: RESULT_(T_LCLIST, ad, e->u.ptr); break; + case EAF_TYPE_CC_ALGO: + RESULT_(T_STRING, s, (const char *) e->u.ptr->data); + break; case EAF_TYPE_UNDEF: RESULT_VOID; break; @@ -758,7 +761,16 @@ case EAF_TYPE_LC_SET: l->attrs[0].u.ptr = v1.val.ad; break; - + case EAF_TYPE_CC_ALGO: + if (v1.type != T_STRING) + runtime( "Setting cc_algo attribute to non-string value" ); + else if (strlen(v1.val.s) >= TCP_CA_NAME_MAX) + runtime( "Setting cc_algo attribute out of bounds (> 15 chars)" ); + /* Store cc_algo string in byte[], making sure to copy the null terminator */ + struct adata *d = lp_alloc_adata(fs->pool, strlen(v1.val.s) + 1); + memcpy(d->data, v1.val.s, d->length); + l->attrs[0].u.ptr = d; + break; case EAF_TYPE_BITFIELD: { /* First, we have to find the old value */ diff --git a/filter/f-util.c b/filter/f-util.c index 410999a6..3cf68270 100644 --- a/filter/f-util.c +++ b/filter/f-util.c @@ -121,6 +121,8 @@ ca_lookup(pool *p, const char *name, int f_type) break; case T_LCLIST: ea_type = EAF_TYPE_LC_SET; + case T_STRING: + ea_type = EAF_TYPE_CC_ALGO; break; default: cf_error("Custom route attribute of unsupported type"); diff --git a/nest/route.h b/nest/route.h index 7930058a..053d2f1e 100644 --- a/nest/route.h +++ b/nest/route.h @@ -587,6 +587,7 @@ const char *ea_custom_name(uint ea); #define EAF_TYPE_INT_SET 0x0a /* Set of u32's (e.g., a community list) */ #define EAF_TYPE_EC_SET 0x0e /* Set of pairs of u32's - ext. community list */ #define EAF_TYPE_LC_SET 0x12 /* Set of triplets of u32's - large community list */ +#define EAF_TYPE_CC_ALGO 0x18 /* String to specify congestion control algorithm */ #define EAF_TYPE_UNDEF 0x1f /* `force undefined' entry */ #define EAF_EMBEDDED 0x01 /* Data stored in eattr.u.data (part of type spec) */ #define EAF_VAR_LENGTH 0x02 /* Attribute length is variable (part of type spec) */ diff --git a/nest/rt-attr.c b/nest/rt-attr.c index c630aa95..b4fdfd85 100644 --- a/nest/rt-attr.c +++ b/nest/rt-attr.c @@ -969,6 +969,9 @@ ea_show(struct cli *c, const eattr *e) case EAF_TYPE_LC_SET: ea_show_lc_set(c, ad, pos, buf, end); return; + case EAF_TYPE_CC_ALGO: + bsnprintf(pos, ad->length, "%s", (char *)ad->data); + return; case EAF_TYPE_UNDEF: default: bsprintf(pos, "<type %02x>", e->type); diff --git a/sysdep/linux/krt-sys.h b/sysdep/linux/krt-sys.h index 8897f889..f265ceb7 100644 --- a/sysdep/linux/krt-sys.h +++ b/sysdep/linux/krt-sys.h @@ -39,7 +39,7 @@ static inline struct ifa * kif_get_primary_ip(struct iface *i UNUSED) { return N #define EA_KRT_SCOPE EA_CODE(PROTOCOL_KERNEL, 0x12) -#define KRT_METRICS_MAX 0x10 /* RTAX_QUICKACK+1 */ +#define KRT_METRICS_MAX 0x11 /* RTAX_CC_ALGO+1 */ #define KRT_METRICS_OFFSET 0x20 /* Offset of EA_KRT_* vs RTAX_* */ #define KRT_FEATURES_MAX 4 @@ -64,7 +64,7 @@ static inline struct ifa * kif_get_primary_ip(struct iface *i UNUSED) { return N #define EA_KRT_RTO_MIN EA_CODE(PROTOCOL_KERNEL, 0x2d) #define EA_KRT_INITRWND EA_CODE(PROTOCOL_KERNEL, 0x2e) #define EA_KRT_QUICKACK EA_CODE(PROTOCOL_KERNEL, 0x2f) - +#define EA_KRT_CC_ALGO EA_CODE(PROTOCOL_KERNEL, 0x30) struct krt_params { u32 table_id; /* Kernel table ID we sync with */ diff --git a/sysdep/linux/netlink.Y b/sysdep/linux/netlink.Y index 487ad1d8..b07fa842 100644 --- a/sysdep/linux/netlink.Y +++ b/sysdep/linux/netlink.Y @@ -14,7 +14,7 @@ CF_KEYWORDS(KERNEL, TABLE, METRIC, NETLINK, RX, BUFFER, KRT_PREFSRC, KRT_REALM, KRT_SCOPE, KRT_MTU, KRT_WINDOW, KRT_RTT, KRT_RTTVAR, KRT_SSTRESH, KRT_CWND, KRT_ADVMSS, KRT_REORDERING, KRT_HOPLIMIT, KRT_INITCWND, KRT_RTO_MIN, KRT_INITRWND, KRT_QUICKACK, - KRT_LOCK_MTU, KRT_LOCK_WINDOW, KRT_LOCK_RTT, KRT_LOCK_RTTVAR, + KRT_CC_ALGO, KRT_LOCK_MTU, KRT_LOCK_WINDOW, KRT_LOCK_RTT, KRT_LOCK_RTTVAR, KRT_LOCK_SSTRESH, KRT_LOCK_CWND, KRT_LOCK_ADVMSS, KRT_LOCK_REORDERING, KRT_LOCK_HOPLIMIT, KRT_LOCK_RTO_MIN, KRT_FEATURE_ECN, KRT_FEATURE_ALLFRAG) @@ -45,6 +45,7 @@ dynamic_attr: KRT_INITCWND { $$ = f_new_dynamic_attr(EAF_TYPE_INT, T_INT, EA_KRT dynamic_attr: KRT_RTO_MIN { $$ = f_new_dynamic_attr(EAF_TYPE_INT, T_INT, EA_KRT_RTO_MIN); } ; dynamic_attr: KRT_INITRWND { $$ = f_new_dynamic_attr(EAF_TYPE_INT, T_INT, EA_KRT_INITRWND); } ; dynamic_attr: KRT_QUICKACK { $$ = f_new_dynamic_attr(EAF_TYPE_INT, T_INT, EA_KRT_QUICKACK); } ; +dynamic_attr: KRT_CC_ALGO { $$ = f_new_dynamic_attr(EAF_TYPE_CC_ALGO, T_STRING, EA_KRT_CC_ALGO); } ; /* Bits of EA_KRT_LOCK, based on RTAX_* constants */ diff --git a/sysdep/linux/netlink.c b/sysdep/linux/netlink.c index 29b744cb..4d4d704b 100644 --- a/sysdep/linux/netlink.c +++ b/sysdep/linux/netlink.c @@ -73,6 +73,10 @@ #define NETLINK_GET_STRICT_CHK 12 #endif +#ifndef TCP_CA_NAME_MAX +#define TCP_CA_NAME_MAX 16 +#endif + #define krt_ipv4(p) ((p)->af == AF_INET) #define krt_ecmp6(p) ((p)->af == AF_INET6) @@ -534,6 +538,9 @@ static inline u16 rta_get_u16(struct rtattr *a) static inline u32 rta_get_u32(struct rtattr *a) { return *(u32 *) RTA_DATA(a); } +static inline char *rta_get_str(struct rtattr *a) +{ return (char *) RTA_DATA(a); } + static inline ip4_addr rta_get_ip4(struct rtattr *a) { return ip4_ntoh(*(ip4_addr *) RTA_DATA(a)); } @@ -624,6 +631,12 @@ nl_add_attr_u32(struct nlmsghdr *h, uint bufsize, int code, u32 data) nl_add_attr(h, bufsize, code, &data, 4); } +static inline void +nl_add_attr_str(struct nlmsghdr *h, unsigned bufsize, int code, char *str) +{ + nl_add_attr(h, bufsize, code, str, strlen(str) + 1); +} + static inline void nl_add_attr_ip4(struct nlmsghdr *h, uint bufsize, int code, ip4_addr ip4) { @@ -880,20 +893,25 @@ err: } static void -nl_add_metrics(struct nlmsghdr *h, uint bufsize, u32 *metrics, int max) +nl_add_metrics(struct nlmsghdr *h, uint bufsize, u32 *metrics, char *cc_algo, int max) { struct rtattr *a = nl_open_attr(h, bufsize, RTA_METRICS); int t; - for (t = 1; t < max; t++) - if (metrics[0] & (1 << t)) - nl_add_attr_u32(h, bufsize, t, metrics[t]); + for (t = 1; t < max; t++) { + if (metrics[0] & (1 << t)) { + if (EA_CODE(PROTOCOL_KERNEL, KRT_METRICS_OFFSET + t) == EA_KRT_CC_ALGO) + nl_add_attr_str(h, bufsize, t, cc_algo); + else + nl_add_attr_u32(h, bufsize, t, metrics[t]); + } + } nl_close_attr(h, a); } static int -nl_parse_metrics(struct rtattr *hdr, u32 *metrics, int max) +nl_parse_metrics(struct rtattr *hdr, u32 *metrics, char *cc_algo, int max) { struct rtattr *a = RTA_DATA(hdr); int len = RTA_PAYLOAD(hdr); @@ -911,7 +929,19 @@ nl_parse_metrics(struct rtattr *hdr, u32 *metrics, int max) return -1; metrics[0] |= 1 << a->rta_type; - metrics[a->rta_type] = rta_get_u32(a); + + if (EA_CODE(PROTOCOL_KERNEL, KRT_METRICS_OFFSET + a->rta_type) == EA_KRT_CC_ALGO) { + char *str = rta_get_str(a); + if (strlen(str) < TCP_CA_NAME_MAX) { + memcpy(cc_algo, str, strlen(str) + 1); + } else { + log(L_ERR "KRT: Received route with cc_algo attribute out of bounds (> 15 chars)"); + return -1; + } + metrics[a->rta_type] = 0; + } else { + metrics[a->rta_type] = rta_get_u32(a); + } } if (len > 0) @@ -1427,6 +1457,7 @@ nl_send_route(struct krt_proto *p, rte *e, int op, int dest, struct nexthop *nh) u32 metrics[KRT_METRICS_MAX]; + char cc_algo[TCP_CA_NAME_MAX]; metrics[0] = 0; struct ea_walk_state ews = { .eattrs = eattrs }; @@ -1434,11 +1465,16 @@ nl_send_route(struct krt_proto *p, rte *e, int op, int dest, struct nexthop *nh) { int id = ea->id - EA_KRT_METRICS; metrics[0] |= 1 << id; - metrics[id] = ea->u.data; + if(ea->id == EA_KRT_CC_ALGO) { + metrics[id] = 0; + memcpy(cc_algo, ea->u.ptr->data, ea->u.ptr->length); + } else { + metrics[id] = ea->u.data; + } } if (metrics[0]) - nl_add_metrics(&r->h, rsize, metrics, KRT_METRICS_MAX); + nl_add_metrics(&r->h, rsize, metrics, cc_algo, KRT_METRICS_MAX); dest: @@ -1907,10 +1943,12 @@ nl_parse_route(struct nl_parse_state *s, struct nlmsghdr *h) if (a[RTA_METRICS]) { u32 metrics[KRT_METRICS_MAX]; + char *cc_algo = lp_alloc(s->pool, TCP_CA_NAME_MAX); ea_list *ea = lp_alloc(s->pool, sizeof(ea_list) + KRT_METRICS_MAX * sizeof(eattr)); + struct adata *d = lp_alloc(s->pool, sizeof(struct adata) + TCP_CA_NAME_MAX); int t, n = 0; - if (nl_parse_metrics(a[RTA_METRICS], metrics, ARRAY_SIZE(metrics)) < 0) + if (nl_parse_metrics(a[RTA_METRICS], metrics, cc_algo, ARRAY_SIZE(metrics)) < 0) { log(L_ERR "KRT: Received route %N with strange RTA_METRICS attribute", net->n.addr); return; @@ -1921,8 +1959,15 @@ nl_parse_route(struct nl_parse_state *s, struct nlmsghdr *h) { ea->attrs[n].id = EA_CODE(PROTOCOL_KERNEL, KRT_METRICS_OFFSET + t); ea->attrs[n].flags = 0; - ea->attrs[n].type = EAF_TYPE_INT; /* FIXME: Some are EAF_TYPE_BITFIELD */ - ea->attrs[n].u.data = metrics[t]; + if (ea->attrs[n].id == EA_KRT_CC_ALGO) { + ea->attrs[n].type = EAF_TYPE_CC_ALGO; + d->length = strlen(cc_algo) + 1; + memcpy(d->data, cc_algo, d->length); + ea->attrs[n].u.ptr = d; + } else { + ea->attrs[n].type = EAF_TYPE_INT; /* FIXME: Some are EAF_TYPE_BITFIELD */ + ea->attrs[n].u.data = metrics[t]; + } n++; } @@ -2225,7 +2270,8 @@ krt_sys_copy_config(struct krt_config *d, struct krt_config *s) static const char *krt_metrics_names[KRT_METRICS_MAX] = { NULL, "lock", "mtu", "window", "rtt", "rttvar", "sstresh", "cwnd", "advmss", - "reordering", "hoplimit", "initcwnd", "features", "rto_min", "initrwnd", "quickack" + "reordering", "hoplimit", "initcwnd", "features", "rto_min", "initrwnd", "quickack", + "cc_algo" }; static const char *krt_features_names[KRT_FEATURES_MAX] = { --- Please also find the patch attached. Thank you, Trisha -- *Trisha Biswas* | Sr. Software Engineer, Network Systems fastly.com | @fastly <https://twitter.com/fastly> | LinkedIn <http://www.linkedin.com/company/fastly>

3 3

Filter based on BGP protocol status ...
by Xavier Trilla 25 Mar '22

25 Mar '22

Hi, I'm quite sure this cannot be done, but I also know there is a lot of BIRD I still don't know, so here it goes: Is there any way to filter a export route based on another BGP session status? For the sake of simplicity let's say we have just two providers A and B, and I only want to export some specific routes to B when A is down. I can do it externally with a quite simple script (For example: Check if the provider is down via CLI and if it's down insert the routes I want to export to a kernel table and export that to provider B) but it would be nice if I could do it directly in Bird. I've been scratching my head around this, but unless there is something like if proto.A == down on the filters I don't really see how to do it (Or maybe some way to raise a global flag based on if I'm receiving routes via provider B, but I don't think that can't be done either.) Thanks for your time! Xavier

7 12